By midsummer of this year, every state in the U.S. will have either embraced marriage equality, or be facing litigation aimed at establishing the freedom to marry, according to the Washington Post.

Minneapolis-based attorney Joshua Newville confirmed to the Post that he and other attorneys are preparing to file a lawsuit challenging North Dakota's constitutional amendment prohibiting same-sex marriage, which was approved by 73 percent of voters in 2004. That suit is expected to be filed in the next six to eight weeks, Newville said.

North Dakota is one of 33 U.S. territories to prohibit same-sex marriage, and the only one whose law has not yet been challenged. Until last week, South Dakota and Montana were also on that list, but challenges were filed in those two states during weeklong tidal wave of marriage equality news starting last Monday.

On May 19, a federal judge in Oregon struck down the state's constitutional amendment banning marriage equality. State officials had refused to defend the law in court, and subsequently announced they would not appeal the decision, allowing same-sex marriages to begin immediately in Oregon.

Also on Wednesday, four same-sex couples filed a federal lawsuit seeking the freedom to marry in Montana, arguing that the state must recognize their existing legal marriages, performed in other states.

With that cascade of good news for committed same-sex couples, 19 states and the District of Columbia now embrace marriage equality. Across the country, there are 70 cases in federal or state court seeking the freedom to marry, including federal appeals of pro-equality rulings in six circuit courts, according to advocacy group Freedom to Marry.

Since the U.S. Supreme Court's landmark rulings last summer striking down the federal Defense of Marriage Act in U.S. v. Windsor, every state and federal court that has considered the issue has ruled in favor of marriage equality, with nearly 20 decisions citing the legal precedent set by Windsor, which framed the freedom to marry as a fundamental right.